Potassium iodide cross-linking inhibitor for n-methylolacrylamide

ABSTRACT

A METHOD FOR INHIBITING CROSS-LINKING OF CELLULOSE WHEN N-METHYLOLACRYLAMIDE IS REACTED WITH CELLULOSIC TEXTILE MATERIALS IN THE PRESENCE OF ACID-ACTING CATALYSTS, WHICH COMPRISES THE USE OF POTASSIUM IODIDE WITH OR WITHOUT CUPRIC CHLORIDE. AN AQUEOUS TEXTILE FINISHING COMPOSITION FOR PERMANENT PRESS CELLULOSIC TEXTILES CONTAINING NMETHYLOLACRYLAMIDE, AN ACID-ACTING CATALYST AND POTASSIUM IODIDE, WITH OR WITHOUT CUPRIC CHLORIDE.

3,558,263 Patented Jan. 26, 1971 3,558,263 POTASSIUM IODIDECROSS-LINKING INHIBITOR FOR N-METHYLOLACRYLAMIDE William FrederickBaitinger, Jr., Hillsborough Township,

Somerset County, N.J., assignor to American Cyanamid Company, Stamford,Conn., a corporation of Maine No Drawing. Filed Oct. 1, 1968, Ser. No.764,347

Int. Cl. C08g 51/56; D06m 13/40 US. Cl. 8-1163 10 Claims ABSTRACT OF THEDISCLOSURE A method for inhibiting cross-linking of cellulose whenN-methylolacrylamide is reacted with cellulosic textile materials in thepresence of acid-acting catalysts, which comprises the use of potassiumiodide with or without cupric chloride. An aqueous textile finishingcomposition for permanent press cellulosic textiles containing N-methylolacrylamidc, an acidacting catalyst and potassium iodide, with orwithout cupric chloride.

This invention relates to permanent press finishes for cellulosictextile materials. More particularly, it relates to a method forinhibiting the cross-linking of cellulose when N-methylolacrylamide isreacted with cellulosic textile materials in the presence of anacid-acting catalyst. It also relates to an aqueous textile finishcontaining N- methylolacrylamide, Zinc nitrate and potassium iodide, andoptionally cupric chloride.

At least three methods have been suggested for the reaction ofcellulosic textile materials with N-methylolacrylamide to obtaincross-linking of the cellulose and a durable press finish. Each of themethods is a 2-step operation, the first step in each case specifyingthe reaction of the cellulosic textile material withN-methylolacrylamide by heating in the presence of an acid-actingcatalyst. The methylol groups react with hydroxyl groups of cellulose toform an ether (Formula 1).

In the second step, further reaction of the cellulose ether (Formula I)is carried out in the presence of (1) a base (U.S. Pat. 2,837,511), (2)a free radical initiator (US. Pat. 3,125,405), or (3) high energyradiation [TeX. Res. J. 35, 648 (1965)]. Two types of reactions arereported, both causing cross-linking of the cellulose, and the fabricacquires permanent press properties. In one type of reaction, the doublebond of the acrylamide moiety reacts with a cellulose hydroxyl group togive a product of Formula II:

FORMULA II Cell CH2CII2HCNHCHQOCcll O In the other type of reaction,homopolymerization occurs at the double bonds to form a polymer in thefiber and attached thereto by multiple ether linkages. In either case,cross-linking of cellulose occurs and the fabric acquires permanentpress properties.

For some purposes, such as deferred cure processes for durable press, itis desirable to keep the two steps separate and distinct; that is, whenthe reaction of the methylol group of N-methylolacrylamide withcellulose is being carried out, reactions of the double bond of N-methylolacrylamide must be prevented. The use of a free radicalinhibitor has been suggested to prevent, or at least minimize, thereactions at the acrylamide double bond. In the absence of a freeradical inhibitor, at least some cross-linking may occur during theacidcatalyzed reaction. This is particularly true when the catalyst iszinc nitrate.

Hydroquinone has been suggested and used as a free radical inhibitor inthe reaction of cellulose with N- methylolacrylamide in the presence ofan acid-acting catalyst. But, hydroquinone causes severe discolorationof white fabrics and shade changes of dyed fabrics when the fabrics areheated in the presence of an acid-acting catalyst, such as zinc nitrate.Other phenolic compounds, such as mono-methyl ether of hydroquinone andp-tertiarybutylcatechol, do not prevent the cross-linking of cellulose.

Therefore, an object of this invention is to provide a method, using aninhibitor which (1) will prevent or minimize cross-linking by reactionof cellulose with the double bond, or homopolymerization at the doublebond, of N-methylolacrylamide when the latter is heated on the fabric inthe presence of an acid-acting catalyst, such as zinc nitrate, and (2)will not cause discoloration of white goods or color change of dyedgoods.

A further object is to obtain permanent pressed white and coloredcellulose goods of good color.

These and other objects of the invention will become apparent as thedescription thereof proceeds.

It has now been discovered that potassium iodide, used either alone orin combination with cupric chloride, acts as a free radical inhibitor inthe reaction of cellulosic textile materials with N-methylolacrylamide.Essentially no cross-linking of cellulose takes place whenNmethylolacrylamide is heated on a cellulosic textile material in thepresence of an acid-acting catalyst and the inhibitor. Also, there islittle or no discoloration of White goods or color change of dyed goods.

Since N-methylolacrylamide and the acid-acting catalyst are normallyapplied to cellulosic textile materials from an aqueous pad bath, it isconvenient to add the inhibitor to the pad bath. The pad bath can beapplied to the textile material by conventional procedures, such aspadding, dipping, spraying, etc. The materials are then dried and heatedat an elevated temperature to effect reaction of the methylol group ofN-methylolacrylamide with cellulose.

The quantities of Nmethylolacrylamide, catalyst and inhibitor depositedon the textile material can be determined from the quantities in the padbath and amount of pad bath solution applied to the textile material.

The amount of N-methylolacrylamide applied to the textile materialshould be between 2% and 20%. preferably between 5% and 10%, based onthe weight of the material.

Although various acid-acting catalysts well known in the art can beused, the preferred catalyst is zinc nitrate. The amount of zincnitrate, calculated as the hexahydrate, should be at least 0.5%,preferably between 1% and 2%, based on the weight of the textilematerial.

The amount of inhibitor used depends on whether the potassium iodide isused alone or in combination with cupric chloride. When used alone, theamount of potassium iodide should be between 0.2% and 2%, preferablybetween 0.5% and 1%, based on the weight of the bath. When used incombination with cupric chloride, the amount of potassium iodide isbetween 0.1% and 1.0%. preferably between 0.1% and 0.5%, and the amountof cupric chloride is between 0.1% and 1.0%, preferably between 0.1% and0.5%, based on the weight of the bath.

After the methylolacrylamide, acid-acting catalyst and inhibitor havebeen applied to the textile material, the material is normally dried andheated at an elevated temperature to cause reaction of the methylolgroup with cellulose. Optionally, the drying and heating operations canbe performed at the same time.

If performed separately, the fabric can be dried at any convenienttemperature, but short drying periods at 200- 230 F. are preferred.

For the heating operation, a temperature of between 250 and 375 F.,preferably between 300 and 350 F., is employed. A curing oven isnormally used, but any conventional method for heating the textilematerial at the required temperature can be employed. The time requiredcan be determined as well known in the art, about 1.5 minutes at 350 F.,for example.

The fabrics, after the heating step, should be rinsed in water to removeunreacted N-methylolacrylamide, catalyst and inhibitor. The fabrics arethen normally dried.

The cellulosic textile materials on which the finish can be appliedinclude all the cellulosic fibers, such as cotton, viscose rayon, linen,ramie, etc., and mixtures thereof. Blends of cellulosic fibers withnoncellulosic fibers, such as polyesters (Dacron), polyamides (nylon)and so forth may be used. The textile material can be in the form ofwoven or nonwoven fabrics, also as yarns, threads, webbing, batting,etc.

The cellulosic textile material obtained by the process of thisinvention can be used in conventional postcuring operations to obtainvery good durable press finishes. Such operations normally include apressing step to impart creases where creases are desired and smoothnesswhere creases and wrinkles are not desired. The fabric is then furtherprocessed (1) by heating in the presence of a suitable catalyst, such asa basic material or a free radical initiator, or (2) by radiationmethods, to effect crosslinking and to impart durable presscharacteristics, including permanence of creases and resistance of flatsurface to wrinkling. These procedures are known to those skilled in theart.

Furthermore, it has been discovered that the postcuring operation can beaccomplished by heating the fabric obtained by the process of thisinvention in the presence of zinc nitrate, which of all the acid-actingcatalysts is believed to be uniquely suitable for effectingcross-linking of cellulose with N-methylolacrylamide.

The following examples are given to illustrate the invention and are notintended to be limitative.

EXAMPLE I Seven aqueous pad baths were prepared, each bath containing15.3% of N-methylolacrylamide, 1.18% of zinc nitrate hexahydrate and theamount of additive shown The pad baths were applied to 80 x 80 cottonpercale by a standard padding procedure. The wet pickup was 85%,indicating the treated fabrics contained 13% of N-methylolacrylamide and0.95% of zinc nitrate hexahydrate. The fabrics were dried at 225 F. for2 minutes and were then heated at 350 F. for 1.5 minutes.

The wrinkle recoveries of the fabrics were measured by AATCC TentativeTest Method 661959T. Wrinkle recovery values below 240 indicate thatminimal crosslinking had occurred.

The results are shown in Table II, Fabrics A-G corresponding to PadBaths A-G, respectively.

TABLE II Wrinkle recovery,

degrees Color This example demonstrates the elfectivenes of potassiumiodide, and the combination of potassium iodide and cupric chloride, asa cross-linking inhibitor, i.e., an inhibitor with respect to thereaction of the double bonds of N-methylolacrylamide.

vAlthough hydroquinone acts as an inhibitor, accompanied bydiscoloration of the fabric, the related phenolics, hydroquinonemono-methylether and p-tertiary-butylcatechol, showed no inhibitiveaction.

While certain specific embodiments and preferred modes of practice havebeen set forth, it will be understood that this is solely for thepurpose of illustration, and that various changes and modifications maybe made without departing from the spirit of the disclosure or the scopeof the appended claims.

I claim:

1. A method for reacting N-methylolacrylamide with a cellulosic textilematerial comprising impregnating the textile material withN-methylolacrylamide, an acid-acting catalyst and .5 to 2% based on theweight of the impregnating solution potassium iodide and heating thematerial at a temperature of between 250 and 375 F.

2. The method of claim 1 where the acid-acting catalyst is zinc nitrate.

3. The method of claim 1 wherein said textile material is shaped andcreased prior to said heating.

4. A method for reacting N-methylolacrylamide with a cellulosic textilematerial as in claim 1 comprising impregnating the textile material withN-methylolacrylamide, an acid-acting catalyst, .1% to 1% based on theweight of the impregnating solution potassium iodide and .1% to 1% basedon the weight of the impregnating solution cupric chloride and heatingthe material at a temperature of between 250 and 375 F.

5. The method of claim 4 where the acid-acting catalyst is zinc nitrate.

6. An aqueous textile finish containing N-methylolacrylamide, anacid-acting catalyst and .5% to 2% by weight potassium iodide.

7. A finish as in claim 6 where the acid-acting catalyst is zincnitrate.

8. An aqueous textile finish containing N-methylolacrylamide, anacid-acting catalyst, .1% to 1% by weight potassium iodide and .1% to 1%by weight cupric chloride.

' 9. A finish as in claim 8 where the acid-acting catalyst is zincnitrate.

10. A cellulosic textile material having permanent press properties asobtained by the method of claim 1.

References Cited UNITED STATES PATENTS 3,434,161 3/1969 Walsh 8-116.3X

FOREIGN PATENTS 1,383,268 11/1964- France 8-116.3

GEORGE F. LESMES, Primary Examiner J. CANNON, Assistant Examiner US. Cl.X.R.

8-l15.7, 120, 243; 38144; ll793.3l; 252397; 260-666.5, 681.5, 29.4

